Syringe



Sept. 1, 1959- HARTLEY 2,902,035

SYRINGE Filed Oct. 10, 1958 INVENTOR. NeweZZ D, 17am Z 6) BY M Mk1ATTORNEYS Unite States The present invention relates to a syringe of thetype having a hollow tube or barrel provided with a restricted orificeat one end and with its other end being open to admit a piston. Thepiston is movable within the tube to provide pressure for ejectingfluids therefrom or a vacuum for introducing fluid through the orificeinto the tube.

At present such syringes are generally manufactured with a glass barreland a glass piston, the outer walls of the piston and inner walls of thebarrel are ground to form a sealing fit therebetween, and thus in effecteach piston and barrel are mated preventing any intermiXing of the twoelements. While these syringes function, such structure is inherentlyexpensive in View of the necessity of forming the sealing fit. Inaddition, such syringes suffer from the inherent common characteristicof glass, namely being fragile and tending to break even with slightblows.

An object of the present invention is to provide a syringe which iseconomical to manufacture and reliable in use without requiring asealing fit to be formed between the barrel and the outer walls of thepiston.

Another object of the present invention is to provide a syringe of theabove type which has a fragile barrel and a relatively rigid,non-fragile piston and for the minimization of possible breakage of thebarrel caused by the piston moving and hitting the barrel.

A further object of the present invention is to enable a barrel of asyringe to have relatively large deviations in dimensions of its innerwall surfaces and to provide a piston with resilient portions whicheffect a seal therewith irrespective of the deviations, thereby enablinga more economical barrel to be used.

In carrying out the present invention, there is provided a barrel of thetype having a restricted orifice at one end, an open end at the otherand a piston operable within the barrel. The cross-sectional shape ofthe inner working portion of the barrel is substantially constantthroughout its length, though it may vary within relatively largetolerances for a syringe barrel. The piston has a crosssectional shapewhich is smaller than the smallest crosssection area of the barrel, andif desired may be many times smaller, it not being essential to thepresent invention that the working length of the barrel have aconstant-shaped or size cross section. Thus a limited amount of movementbetween the piston and the barrel in a direction perpendicular to theaxis of the piston occurs.

In order to form the seal, the piston is provided with a groove adjacentits working end (with the other end being formed to provide a handle)and within this groove there is positioned a ring of resilient material,such as rubber. The normal, outside periphery of the ring is larger thanthe largest cross-sectional shape of the working length of the barreland hence upon insertion of the piston within the barrel the ring iscompressed and forms a seal between the piston and the barrel.

When the barrel is formed of fragile material, such as glass, and thepiston is formed of rigid material, such as atent f Patented Sept. 1,1959 metal, the ring forms, in addition to a seal, a resilient bumperbetween the two elements at the place where it is positioned on thepiston, thereby preventing the piston from damaging the barrel. However,when the piston is completely or almost completely within the barrel,then the handle end of the working portion of the piston has room tomove and has a tendency upon such jarring of the syringe to hit thebarrel and cause breakage thereof. This is obviated according to thepresent invention by forming an annular groove adjacent the handle endof the working portion of the piston and positioning within this groovea ring of resilient material similar to that used at the working end ofthe piston. This ring serves as a resilient bumper between the barreland the piston to cushion movement of the piston and prevent it fromshattering the fragile barrel.

The second resilient ring in addition to achieving the above objectfurther aids in preventing breakage of the barrel by the piston duringuse. The second ring also forms a seal with the barrel; however, thisseal only occurs when the piston is almost completely within the barrel.This is decidedly advantageous since, as the piston moves into thebarrel and approaches its final position, the second ring causes anadditional force resisting movement of the piston which tends to preventthe working end of the piston from hitting the restricted end of thebarrel with sufiicient force to break the barrel.

While it has been found that one resilient ring is sufficient to formthe seal, a third resilient ring may be positioned between the rings ateach end of the working portion of the piston if this portion isrelatively long or if there is too much play between the piston and thebarrel at intermediate positions of the barrel.

Other features and advantages will hereinafter appear.

In the drawings:

Figure 1 is a sectional view taken along an axial section of a syringeconstructed according to the present invention.

Fig. 2 is a view of the barrel and its resilient members.

Fig. 3 is a view taken on the line 33 of Fig. 1 in the direction of thearrows.

Referring to the drawing, the syringe of the present invention generallyindicated by the reference numeral 10 consists of a hollow barrel 11 anda piston 1'2 operable therein. The barrel ll at one end has inturnedportions 13 defining a reduced orifice 14 leading outwardly through aneck 15. A head 16 is formed on the exterior of the neck 15 to increasethe sealing engagement thereof with an end portion of a piece of pliablehose 17.

The other end of the barrel is open as at 18 and between the opening 18and the portions 113 the barrel has a substantially circular crosssection as indicated in Fig. 3, though, of course, it may be oval ifdesired. The inner walls of the barrel 11 between the opening 18 and theinturned portion 13 is referred to as the working portion of the barrelsince the piston works within this portion. The cross-sectional shape ofthe Working portion is substantially identical throughout its length;however, it may have relatively large tolerances (for a syringe barrel)to enable a more economical barrel to be used. Flanges l? are formedadjacent the opening 18 to enable the user to grasp the barrel.

The piston 12, as shown in Fig. 2, has a working or operating portionwhich is specifically shown as having a substantially cylindrical lengthfor a distance which is approximately equal to the working length of thebarrel. A handle 20 is formed at one end of the working portion of thebarrel and may have any shape desired; however, in the disclosedembodiment, it is merely a circular knob connected to the workingportion.

A radial peripheral groove 21 is formed in the piston adjacent theworking end of the piston and a similar portion .ofnthe ebarrel therebyCallSiDg,1.'Wl1H:Ith6f3 rings :1

engage: the. barrel; a compressioinohtheringss;a com-a;pressionzcauses;a seal :betweenvthe ringsxand the: barrel; which im the;case-of .the-..ring:1nearest; the. workingcendsof,

the:-piston:is Sllfi'lClEIli'ztO create a seal between theaba'rrel'il.andithe-piston evenrwith ithe' relatively largextolerancesin. :1

the vcross-sectional:shape of tthe ibarrela It iwillrthusnbezappreciatedthamonlyone. :ring (23f)is necessary. lIOCIEEte...

the sealing-fit;

In the: disolosedaembodiment of:the invention zthew barrelc-ll. isformed-f fragile lmaterial; glass; and the a.

piston is formed of anodized aluminum and-hence is :a rigidnon-resilient :ma-terial. Wit-h only; a single--O-r1ng adjacent.theworking;.end: of :the .piston-andvwith the piston completely-withinthe:-ba-rrel,.the other-end of thee:

piston adjacent, the opening 118: can move laterally: This movement or-zplay is :such. that .inthe-case *whenvrthe syringe is abruptly moved,--it may.causebreakageofithe barrelby thepiston-hitting it..

According. to -.-.the.- present; invention;- however, there:silient-iring 24;ser-.ves as a burnperwbetweenthe piston andir the..barrel' and :obviates breakageg. caused-.zby :lateral :move-:

ment of the piston:

When; in .-=use,: as ..-the. ,piston is introduced:- and forced downthebar-rel towards-the neck portion 15, the only-- resistive force iscaused by engagement betweenthei ring 23-1and the. barrel (excluding theeffect of any fluid presew sureslsandihence there is a tendency.fort-the piston to :1 maintain its speed andgtothit the portion- .13sWith::a.

forceswhich. may. be great enough to break: the portion 13. The ring 24positioned on the pistons to engagegthe inner .Walls of the barrels.prior to the. piston being: $301111 pletelytwithin the barrelobviatesthis condition -'.by.-in-.-

creasing the resistive force to movement of the piston. Thus.thissecond: ring t24rtendsto prevent the: piston .from hitting the.enchofx the barrel=witht a forceisufficientto break it.

In syringes,.-.which. have.a relatively longworking lengtlnandlsorelativelylong operating lengths .of. the

piston,. it is at,times desirable to addra third resilient member which.may .bean O-ring r25 .positionedbetween Y the:.other..two, preferablycentered therebetween .to limit playrofitheltpiston.during, and at itsintermediate position.-.. Thisthird .O-ring..which..is similar. to :therings:

23 and 24 is positioned: and maintainedin a groove 26-.

similar. to the. groovesll and 22 and operates in the samevmanneras-thesecond O-ring 24 to perform the.

same; functions.

It will accordinglybe appreciated that there has been disclosed a:syringe that. is relatively economical to manufacture, which. isreliable in use over an extended period andin which the tendency. of afragile barrel to be broken by. a rigid piston is substantiallyminimized.

Variations. andmodifications may be made withinthe. scope. of. the.claims andportions of the. improvements may beused without others.

I claim:

1. A syringe comprising a hollow barrel having a restricted.orificeformed in one end'and the other end beingopenanddefining. anopening having a cross-sectional shape,..said barrel having. anoperating length with..its inner walls defining .a cross-sectional shapethroughout the.. length which. is substantially identical to.thdcross-sectional shape of the opening,- a piston.

formed .of.relatively..rigid. materiaL-having an operating portion and ahandle portion extending. from one end of theroperating portion; the;length of'the operating poraaoaoss t p v.

tion being at least as long as the operating length of the barrel, aperipheral ring -grooveformed in the piston r.- adjacent one end of theoperating portion, a second radial peripheral groove formed in theoperating portion of the piston and spaced from the first groove adistance slightly less than the operating length of the barrel, and aring of resilient material positioned and maintained in each groove, theperiphenyrof the rings being larger than the periphery of the opening ofthe barrel and being compressed by the operating length of the barrelupon engagementwtherewith wasathe;operating-length of the piston isinserted into the barrel to cause a seal therebetween:

2. A syringe comprising a .barrel .having a hollow cylindrical operatinglength provided with a restricted orifice formed in one end and theother end being open and defining a substantially circular opening, apiston formed of relatively rigid material to have an operating portionand-a handle'-portion,-the' operatingportionebeing at least as long: asthe-length of the hollow operating length of:the-barrel, a radialperipheral groove formed" in the piston adjacent one end'oftheoperating=portion;--" a second radial peripheral groove for'medinthei operating-- portion of the-piston and-spaced tro-m-thefirst groove'a distance slightly less than the operating length of the barrel,-and-a ring ofaresilient material-positioned=andmaintainedin each groove,the'diaimeter of' the rings-beinglarg Y er than-thediameter of:theopening and -being=com-pressedbythe operating :lehgth oft the barrelupon .tengagement therewith asthe operating -length:of the 'pistonisinserted into the barrel to cause a seal therebetween.

3. 'A syringew' comprising a -hollow barrel havingarestricted-i-orificetormed: in one end rand the'- other '-end 5 beingopen and defining anaopening-having a cross sec tionalshape; said barrelhavinganoperating length with 11 its inner walls defining across-sectional shape throughout the'iengthwhich is substantiallyidentical to the cross-sectional shape: of:the opening; a pistonformedof relativelw rigidimaterialihaving an operating portionend-ahandle portion extendingfrom-zone end of-the' operatingportiony the 1length not; the operating: portion :beingat least as longastthe:.operating' length ofrthe barreL -a peripheral 1 ring groove.formed; in: :the piston uadjacent i one t end -of theoperatingportion',a second-radial peripheral grooveformed in the operatingaportion' ofthepistonandspaced fromthe firstgroove-a distance; slightly less than=theoperating 'lengthzof:the"barrel',-za third peripheral ring" grooveformed in rthei-operatingportion of the piston between the other "twogIO0Y6S,ii&Hd' a ring ofxr'esilient material positioned. and amaintained .iILL each; groove; the peripheryof: the rings being largerthan the peripheryof the openingof the. --.barrelianddbeing; compressed:by :the operating length of .the; barrehuponengagement:therewith asztheoperating length.of;.the-.piston:.is.inserted into thebarrel-to cause aseabtherebetween:

4. =A.syringe zcomprisingra barrel havinga hOl-IOVTCYHm? drical:operating-lengthiprovided with: a restricted :orifice formed-.in oneendaandihe othervendbeing'topen and-de fin-inga. substantiallycirculanopening, ;a piston aformed'ofij relatively.rigidrmaterialtmhavean-.operating .portionwand a handle. portion, :the; operating portion;being at: least as-long;as-. the length of:the hollow aoperating lengthofi the; barrel, :a radialzperipheral groove formed'in the piston":adjacent .one endofrthejoperating portion;. .a second radialr peripheralgrooveformedin. the operatingportion of-theiw piston and;spaced;from;the:first:groove a distancezslighta lyllessthan theoperatingwlengthi of the barrel', a third :3 radial peripheralxgrooveformed; in the operating '.portion,:i of:the pistombetween.the ;othertwogrooves,:and:a ring of resilient material. positioned and; maintainedin. reach" z..= groove; thei-diameter ofthe; rings ;.being.;larger than;the: diameter of: :the: opening-and beingv compressed by the: operatinglength .of the barrel :upon engagement ;ther.ewith l5= as the operatinglength of the piston is insertedinto 11116 barrel to. causeua seal.:therebetween;

5. The invention as defined in claim 1 in which the rings are toroidalhaving a circular cross-section and are formed of rubber.

6. The invention as defined in claim 1 in which the barrel is formed ofglass and the piston is formed from aluminum.

7. The invention as defined in claim 6 in which the rings are toroidalhaving a circular cross-section and are formed of rubber.

References Cited in the file of this patent FOREIGN PATENTS 19,848 GreatBritain July 24, 1913 749,995 France May 15, 1933 974,009 France Sept.20, 1950

